Method and apparatus for treating a solid material



L. T. WORK April 15, 1958 METHOD AND APPARATUS FOR TREATING A SOLIDMATERIAL Filed May 18, 1953 Fill GPA /Vl/L A E VA POR/ZZ/ PPODUCTINVENTOR.

United METHD AND APLARA'EUS FOR TREATliNG A SLBD MATERIAL Lincoln T.Work, Maplewood, N. J., assigner' to Texaco Development Corporation, NewYork, N. Y., a corporation ot Delaware Application May 18, 1953, SerialNo. 355,751

10 Claims. (Cl. 241-5) The present invention relates to a novel methodof and apparatus for treating a solid material, as by pulas talc, coal,barile, and oyster shells, the pulverized` product usually beingrecovered in a substantially dry condition. The passing of a slurrythrough an externally heated tube in which the liquid is vaporized has.also been suggested for distilling volatile materials from acarbonaceous substance such as coal; and for chemically reacting thecoal with vapor.

When heating a liquid slurry by applying heat to the outside of a tube,the heating efficiency is low and the gaseous products of combustion areof no value in propelling the particles along. Also, solid particles maydeposit on the tube walls in the slurry zone when external heating isemployed, in some instances to such an extent as to plug the tube. It isbelieved that such deposition occurs because the externally heatedtubular walls are so hot that local vaporization of liquid occurs at theWalls in the slurry zone even when the remainder of the slurry is stillin liquid form, with the result that the solid particles from which theliquid has vaporized accumulate on the walls as a scale.

In accordance with the present invention there is provided a novelmethod for treating a liowable mixture such as a slurry in such a waythat the advantageous results of the prior art are obtained Whileobtaining higher heating and propelling efliciency and avoiding theundesirable deposition of solid particles on the walls of the tube.These desirable results are obtained by providing a slurry of particlesof solid material in a liquid, then passing the slurry into a Vaporizingchamber wherein the slurry is eiciently heated internally by directcontact with a heating element, such as a flame within the chamber, tovaporize liquid and form a dispersion of solid particles in a flowingstream of vapor, and thereafter discharging the dispersion from thechamber. After dis, charge the dispersion can be treated in any desiredWa as by passing it through a long heated tube within which theparticles are ground, or within which the distillation of volatiles orchemical reactions with the vapor can occur. After treatment in the longtube the dispersion can be discharged into a suitable separator ofconventional type, such as a cyclonewithin which the hot vaporsincluding any distilled volatile material and gaseous products ofchemical reaction are separated from the solid product.

By following the procedure described above, the deposition of solidparticles from a slurry on the walls of the system is prevented sincethe Walls themselves are $30,769 Patented Apr. l5, 1958 not directlyheated but remain relatively cool while the slurry is heated directly bythe ame. Consequently, there is always liquid present to wash the wallsclean. This is true even when the liquid has been partially vaporizedsince the relatively cool Walls condense any vapor coming into contacttherewith and the condensate washes the walls. By relative coolness ofthe vaporizing chamber walls is meant that they are maintained at atemperature sufticiently lower than the boiling point of the liquid thatthe condensation of vapor occurs. This condition can prevail even thoughsome external heating of the vaporizer may be employed at sorne pointsalong the tube for greater efficiency.

The method of `internal heating described above is additionallyadvantageous because the gaseous products of combustion from the heatingflame within the vaporizing chamber flow with the dispersion andincrease its velocity, while at the same time assisting the formation ofa dry solid product. Also, for a given relation of pressure' andvelocity, the cooled gases and vapor may operate atsubstantially lowertemperatures.

Among the materials which can be treated successfully by the method ofthis invention are carbonaceous materials such as coal, noncarbonaceousminerals such as limestone, gypsum, chalk, clay, marl, talc, and bariteThe invention will be described more in detail below inA connection withthe accompanying drawings, wherein:

Figure l is a schematic side elevational viewparts` being broken awayand shown in section, of an arrangement of apparatus for performing themethod of the invention; and

Figure 2 is a longitudinal sectional view of an internalcombustionburner which can be used in the apparatus of Figure l.

With reference to Figure l, a slurry of solid material in liquid isprovided as by mixing the liquid and granular solid together in a slurrymixer 1l. From the mixer 11 the slurry passes in a continuous streamthrough a pump 13 to a pressurized preheater chamber l5 having anagitator 17 for keepingthe solids suspended, and a heating coil 19through which hot fluid is circulated to heat the slurry to a hightemperature. The linear velocity of slurry flow through pump 13advantageously may be between 1/2 and l feet per second.

From the preheater l the slurry liows continuously by way of a conduit2l into a vaporizer chamber 23 containing an axially disposed burnerwhich is supplied with a fluid 'fuel such as kerosene, butane, or fueloil through a conduit 27, and with a combustion supporting fluid such asair or oxygen through a conduit 29, The burner 25 advantageously facesin the direction of slurry ow through the vaporizer 23 so that the highvelocity gaseous products ot combustion in the flame serve to entrainfluid and impcl it in the desired direction, thus expediting the flowsof the slurry and subsequent vaporous dispersion.

As shown in Figure 2, the fuel and combustion supporting gas mixtogether in a throat 3l in burner 25 and pass into an internalcombustion chamber 33 within which combustion at a high temperature ismaintained. Ignition is initially accomplished by a spark plug or otherconventional igniting device. The hot flaming gaseous products ofcombustion leave chamber 33 at high velocity through a discharge passage35 for heating the slurry. The discharge passage 3S advantageously isshaped as a convergent-divergent nozzle so as to give the hot gases asupersonic velocity for assisting the ow of slurry and dispersion.

Slurry Hows in the vaporizer chamber Z3 through the annulus surroundingburner 2S in intimate contact thcrewith so as to cool the burner whileheating the liquid. When the liquid comes into contact with the flame 3)below the burner it is rapidly heated to its vaporization temperaturewith the resultant form-ation of a dispersion of solid particles invapor which is then discharged from the vaporizer chamber through adischarge conduit 3Q.

It is also possible to heat the slurry to vaporization in preheater l5and then superheat the resulting dispersion in chamber 23. Also, insteadof having the burner in the chamber 23 it is possible to feed the hotgases in from a remote point.

In the modification shown in Figure 1 the iiowing dispersion passes byway of the conduit 39 into a heating zone 41 which may comprise a tube,having substantial length compared to its inside diam-eter, heatedexternally by a gas or oil flame within a furnace 43. This heatmaintains the temperature of the dispersion well above the boiling pointof the slurry liquid within the tube and causes the dispersion to liowat a high velocity to efect grinding, drying, distillation, or chemicalreaction, as desired. Of course, one or more internal combustion burnerssimilar to that of Figure 2 could also be located within the tube 41instead of or in addition to the external heating of the tube.

Heating zone 41 may be located in a tube having any desiredconfiguration, such as straight or coiled or arranged as a series ofparallel tubes having return bends. For grinding, the linear velocityshould exceed feet per second which is about the minimum` velocity forcarrying many materials through a tube. As a practical t matter, toassure rapid and substantial disintegration adequate for commercialoperation, the velocity is usually maintained above 100 feet per secondand may sometimes be as high as one to several thousand feet per second.

When only pulverization of the solid particles is desired, conditionsshould be such in the tubular Zone 413. that the solid particles remainsubstantially unchanged chemically as they pass through. In the case ofchemically stable materials such as talc, clay or barite, the primaryconsideration is to maintain the temperature low enough to preventphysical damage to the equipment. Materials that are stable chemically`can be disintegrated up to l,400 F. under low pressure without damagingthe equipment, but high pressures may require lower temperatures such asa 1,200 F. maximum; Less stable materials may require lower maximumtemperatures. For example, volatiles may be distilled off and somechemical reaction with vapor may occur when grinding anthracite coalabove 1,100 F., bituminous coal above 850 F., and lignite above 700 F.

Of course, when the distillation of volatiles or chemical reaction withthe vapor is desired, then the temperature should be maintained abovethe minimum values mentioned above for the less stable materials such ascoal.

The dispersion is discharged from the heating zone 4l. through a conduit45 into a separator 47 such as a conventional centrifugal cyclone,'at/herein the hot vapor is separated and discharged through a conduit49 at the top of the cyclone, and the hot solid material is dischargedfrom the bottom through a discharge conduit 5i. in a substantially drycondition. Y

The hot vapors pass by way of conduit 49 to the heating coil 19 withinpreheater 15 and thus eiect substantial heat economy by exchanging theirheat with the incoming slurry. From the coil 19 the hot vapors leave byway of a conduit 53 and can be collected and used in any desired way.Additional hot gas can be supplied to coil 19 by a conduit 5l. Ifdesired, the hot exhaust gases from conduit 49 can be discharged intopreheater 3.5 for direct contact heating of the slurry.

Water is generally the liquid used for preparing a siurry. However,other liquids which can be used successfully arehydrocarbons such askerosene, and vother liquids such as coal tar distillates, alcohols,glycols, mercury,

diphenyl, carbon tetrachloride, and the like. Water and oil mixturessuitably in the form of emulsions may also be used in preparing theslurry. Hydrocarbon liquids such as kerosene are particularly valuablewhen grinding a material such as aluminum or magnesium which tends toreact with steam, since they are inert to such materials.

The solid particles combined with liquid to form a slurry should be ofsuch size that they can be passed through the tubular heating zonewithout dimculty, for example, having a diameter less than 1A; theinternal diameter of the tube 41. To assure a stable slurry it ispreferably to use particles smaller than about 1A; inch in averagediameter.

The proportion of liquid mixed with the solid to form a slurry may varyconsiderably but generally is less than 2:1 by volume, often being about1:1.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spiritand scope thereof, and therefore only such limitations should be imposedas are indicated in the appended claims.

I claim:

l. A method for pulverizing particles of a solid disintegratablematerial comprising providing a avorable mixture of particles of saidsolid material in a vaporizable liquid; passing said mixture into avaporizing chamber; heating said mixture by direct contact with aheating flame in said chamber to vaporize liquid and form a dispersionof soli-d particles in a flowing stream of vapor; andpassing saiddispersion through a pulverizing zone at a velocity greater than 25 feetper second in highly turbulent ow to effect reduction in the size ofsaid particles.

2. A method in accordance with claim l, also comprising maintaining thetemperature of said dispersion well above the boiling point of saidliquid during passage thereof through sad pulverizing zone by heatingsaid pulverizing zone.

3. A method for treating a solid material comprising providing aflowable mixture of particles of said solid material in a liquid;passing said mixture into a Vaporizing chamber; heating said mixture bydirect contact with a heating element within said chamber to vaporizeliquid and form a dispersion of solid particles in a tiowing stream ofvapor; discharging said dispersion from said chamber; and passing saiddischarged dispersion through a heated tube.

4. A method for treating a solid material comprising providing afiowable mixture of particles of said solid material in a liquid;passing said mixture into a vaporizing chamber; heating said mixture bydirect contact with a heating element within said chamber to vaporizeliquid and form a dispersion of solid particles in a flowing stream ofvapor; discharging said dispersion from said chamber; separating thevapor from the solid particles of said dispersion after dischargethereof from said chamber; and passing the separated vapor in heatexchange relationship with said mixture to preheat the latter before itenters said chamber.

5. Apparatus for treating a solid material comprising lirst means forforming a flowable mixture of particles of 'said solid material in avaporizable liquid; a vaporizing chamber in communication withv saidfirst means for receiving a stream of mixture therefrom; a heaterassociated with said Vaporizing chamber for introducing heat into directcontact with said mixture to vaporize liquid and form a dispersion ofsolid particles in a. flowing stream of vapor; an outlet for dischargingsaid dis-v persion from said chamber; a preheater between said firstmeans and said vaporizing chamber for preheating said mixture beforeentering said vaporizing chamber; and means connected to said outlet forseparating vapor from solid particles of said dispersion after dischargethereof from said chamber, said last named means having an outlet forvapor connected to said preheater for preheating said mixture with saidvapor.

6. Apparatus for treating a solid material comprising first means forforming a owable mixture of particles of said solid material in aVaporizable liquid; a vapori1zing chamber in communication with said rstmeans tor receiving a stream -cf said mixture therefrom; means forpassing a continuous stream of mixture through said chamber; a heaterassociated with said vaporizing chamber operable for introducing aheating medium into said chamber in direct Contact with said mixture tovaporiae liquid and form a dispersion of solid particles in a flowingstream of vapor, said heater being an internal combustion burner locatedWithin said chamber in spaced relation to the Wall of said chamberwhereby mixture` lows in contact with said burner to cool said burner;and an outlet for discharging said dispersion from said chamber.

7. Apparatus in accordance with claim 6 also comprising an elongatedtube connected to said outlet, and means for heating the dispersionowing in` said tube.

8. A method for pulverizing particles of a solid disintegratablematerial comprising providing a iiowable mixture of particles of saidsolid material in a Vaporizabie liquid; passing said mixture into aVaporizing chamber, heating said mixture by direct contact with aheating ame in said chamber to vaporize liquid and form a dispersion ofsolid particles in a flowing stream of vapor; passing said dispersionthrough a succeeding zone of high velocity iiow, and subjecting theflowing stream therein to turbulence and a velocity of the order of atleast 25 feet per second thereby effecting disintegration of saidparticles; and discharging from said succeeding zone of high velocityflow. said stream containing finely ground solids suspended therein.

9. A method in accordance with claim 3 wherein the heating of saidmixture is accomplished by providing an internal combustion burnerwithin said chamber, wherein said heating element is a ame produced byburning a combustible mixture within said burner and discharging saidlburning combustible mixture therefrom, and wherein said flowablemixture flows in direct contact with said burner to cool said burner.

10. A method in accordance with claim 3, wherein said l "ng element is aflame produced by burning a combos 1e mixture, and wherein thecombustion gases ow at high velocity in the same direction as saidflowlable mixture to entrain Huid and impel it in said direction thusexpediting the ows of the owable mixture and subsequent vaporousdispersion.

References Cited in the file of this patent UNITED STATES PATENTS Re.16,749 Holliday Sept. 27, 1927 729,009 Sutton et al. May 26, 19031,471,765 Wilson Oct. 23, 1923 1,475,502 Manning Nov. 27, 1923 1,574,950Wade Mar. 2, 1926 1,759,702 Koon May 20, 1930 2,142,983 Thurman Ian. 3,1939 2,184,300 Hodson et al Dec. 26, 1939 2,306,462 Moerman Dec. 29,1942 2,441,613 Balassa May 18, 1948 2,560,807 Lobo July 17, 19512,568,400 Kearby Sept. 18, 1951 2,640,761 Wiseman June 2, 1953 2,669,509Sellers Feb. 16, 1954 2,712,351 Roth July 5, 1955 UNITED STATES PATENTOFFICE CERTIFICATE 0F CORRECTION Patent No. 2,839,769 Apri 15, 1958Lincoln T. work It is hereby-certified that 'error appears in theprinted spcification of the above numbered patent requiring correctionand that the said Letters Patent should read as corrected below.

Column A, line 2A, fr 1fil.':Lvcmjahle'l read -ffflowable Signed andsealed this 27th day of May 1958.

SEAL) ttest:

ROBERT c. WATSON 'ttesting Officer Conmssioner of Patents

1. A METHOD FOR PULVERIZING PARTICLES OF A SOLID DISINTEGRATABLE MATERIAL COMPRISING PROVIDING A FLAVORABLE MIXTURE OF PARTICLES OF SAID SOLID MATERIAL IN A VAPOR IZABLE LIQUID; PASSING SAID MIXTURE INTO A VAPORIZING CHAMBER; HEATING SAID MIXTURE BY DIRECT CONTACT WITH A HEATING FLAME IN SAID CHAMBER TO VAPORIZE LIQUID AND FROM A DISPERSION OF SOLID PARTICLES IN A FLOWING STREAM OF VAPOR; AND PASSING SAID DISPERSION THROUGH A PULVERIZING ZONE AT A VELOCITY GREATER THAN 25 FEET PER SECOND IN HIGHLY TURBULENT FLOW TO EFFECT REDUCTION IN THE SIZE OF AID PARTICLES. 